In Britain, an influential group of MPs says it is not possible to see how the Irish border issue can be resolved.
Once the United Kingdom leaves the European Union, it'll follow different trade and customs rules than the Republic of Ireland, which is still in the EU.
The report also criticized proposals for technological infrastructure to smoothen any border-checks as "untested" and 'vague.' The Chairman of the committee, prominent Labour Remain MP Hilary Benn shared its sentiments with the BBC on December 1.
Avoiding a so-called "hard border" on the island of Ireland is the last major hurdle before Brexit talks can move to negotiations on Britain's future trade relationship with the European Union and a possible two-year Brexit transition deal.
United Kingdom government ministers have suggested technology could enable a "frictionless border", but the Irish government - with the backing of European Union member states - says it is not persuaded by British assurances that a hard border will not return.
All sides have insisted that there can be no return to a hard border, and the Taoiseach Leo Varadkar has made it clear that Ireland will block the talks from moving forward unless a solution is "written down in practical terms in the conclusions of phase one".
The Exiting the EU Committee in the House of Commons said it appeared impossible to marry the decision to pull out of the single market and customs union with the intention to create a "frictionless" border.
Britain's Prime Minister, Theresa May, poses for a photograph with Democratic Unionist Party (DUP) Leader Arlene Foster, Deputy Leader Nigel Dodds, and Chief Whip Jeffrey Donaldson, outside 10 Downing Street, in central London, Britain June 26, 2017.
"If there is any hint that in order to placate Dublin and the European Union they're prepared to have Northern Ireland treated differently to the rest of the United Kingdom, then they can't rely on our vote", DUP member of parliament Sammy Wilson said in an interview with the BBC.
In fact, both Northern Ireland and Scotland voted to remain in the European Union by margins of 55.8% and 62% respectively.
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